Method and apparatus for transport block signaling in a wireless communication system

ABSTRACT

User equipment determines a transport block size column indicator representative of a number of resource blocks based on a number of allocated resource blocks, an adjustment factor, and a limiting factor. The transport block size column indicator is determined by applying the adjustment factor to the number of allocated resource blocks and comparing a result of applying the adjustment factor to the number of allocated resource blocks to the limiting factor. The transport block size column indicator is selected as either the result or the limiting factor as the based on the comparison.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/869,996, filed Apr. 25, 2013, which claims benefit under 35U.S.C. 119(e) from co-pending U.S. Provisional Application No.61/649,247, filed May 19, 2012, the disclosures of which are herebyincorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to wireless communications and,more particularly, to determination of transport block size (TBS) usinga TBS look-up table in a wireless communication terminal and methods.

BACKGROUND

In 3GPPP LTE Rel-8/9/10, a UE determines the transport block size (TBS),which translates to a corresponding data rate, associated with aphysical downlink shared channel (PDSCH) or a physical uplink sharedchannel (PUSCH) based on downlink control information. The downlinkcontrol information indicates an number of assigned Resource Blocks(RBs) and location in a carrier and a Modulation and Coding Scheme (MCS)index. Based on the number of assigned RBs and MCS index, the UEdetermines the associated transport block (TB) size using a TBS lookuptable (LUT). The LUT in LTE Rel-8/9/10 was designed assuming a referenceconfiguration (PCFICH=3, (that is, a control region of 3 OFDM symbolswith the first data symbol starting on the 4^(th) OFDM symbol), 2 CRSports, normal subframe, with normal CP) and a set of reference MCSs.

The various aspects, features and advantages of the invention willbecome more fully apparent to those having ordinary skill in the artupon careful consideration of the following Detailed Description thereofwith the accompanying drawings described below. The drawings may havebeen simplified for clarity and are not necessarily drawn to scale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a wireless communication network.

FIG. 2 is block diagram of a sequence of radio frames each comprising aseveral subframe frames.

FIG. 3 is a diagram of a message conveying an index to a mobile stationin accordance with the embodiments.

FIG. 4 is a diagram an exemplary format of a Downlink ControlInformation element for providing an index to a mobile station inaccordance with the embodiments.

FIG. 5 is a table 500 which is an exemplary portion of a TBS/MCS tablein accordance with various embodiments.

FIG. 6 is a block diagram of a mobile station in accordance with variousembodiments.

FIG. 7 is a process flow diagram.

DETAILED DESCRIPTION

In FIG. 1, a wireless communication system 100 comprises one or morefixed base infrastructure units 103 forming a network distributed over ageographical region for serving remote units in the time, frequency orspatial domain or a combination thereof. A base unit may also bereferred to as an access point, access terminal, base, base station,NodeB, enhanced NodeB (eNodeB), Home NodeB (HNB), Home eNodeB (HeNB),Macro eNodeB (MeNB), Donor eNodeB (DeNB), relay node (RN), femtocell,femto-node, pico-cell, network node, a transmission point or by otherterminology used in the art. The one or more base units each compriseone or more transmitters for downlink transmissions and one or morereceivers for uplink transmissions. The base units are generally part ofa radio access network that includes one or more controllers 109communicably coupled to one or more corresponding base units via links111. The access network is generally communicably coupled to one or morecore networks, which may be coupled to other networks like the Internetand public switched telephone networks among others. Regardless ofspecific implementations, the base station controller 109 comprisesvarious modules for packetized communications such as a packetscheduler, packet segmentation and reassembly, etc., and modules forassigning appropriate radio resources to the various mobile stations101. The RAN may also support circuit switched communications inaddition to packet-based communications wherein the circuit and packetswitched communication utilize different communication protocols. Theseand other elements of access and core networks are not illustrated butare known generally by those having ordinary skill in the art.

In FIG. 1, the one or more base units serve a number of remote units,for example unit 101, within a corresponding serving area, for example,a cell or a cell sector, via a wireless communication link. The remoteunits may be fixed or mobile. The remote units may also be referred toas subscriber units, mobiles, mobile stations, mobile units, users,terminals, subscriber stations, user equipment (UE), user terminals,wireless communication devices, relay node, or by other terminology usedin the art. The remote units also comprise one or more transmitters andone or more receivers. In FIG. 1, the base units transmit downlink (DL)communication signals on a radio link 105 to serve remote units in thetime, frequency, code and/or spatial domain. The remote unitscommunicate with base unit via uplink (UL) communication signals on theradio link 105. Sometimes the base unit is referred to as a serving orconnected or anchor cell for the remote unit. The remote units may alsocommunicate with the base unit via a relay node.

In one implementation, the wireless communication system is compliantwith the 3GPP Universal Mobile Telecommunications System (UMTS) LTEprotocol, also referred to as EUTRA or 3GPP LTE or some later generationthereof, wherein the base unit transmits using an orthogonal frequencydivision multiplexing (OFDM) modulation scheme on the downlink and theuser terminals transmit on the uplink using a single carrier frequencydivision multiple access (SC-FDMA) or Discrete Fourier Transform-spreadOFDM scheme. The instant disclosure is particularly relevant to 3GPP LTERelease 11 (Rel-11) and later versions thereof, but may also beapplicable to other wireless communication systems. More generally thewireless communication system may implement some other open orproprietary communication protocol, for example, IEEE 802.16(d) (WiMAX),IEEE 802.16(e) (mobile WiMAX), IEEE 802.11 (WiFi) among other existingand future protocols. The architecture may also include the use ofspreading techniques such as multi-carrier CDMA (MC-CDMA), multi-carrierdirect sequence CDMA (MC-DS-CDMA), Orthogonal Frequency and CodeDivision Multiplexing (OFCDM) with one or two dimensional spreading. Thearchitecture in which the features of the instant disclosure areimplemented may also be based on simpler time and/or frequency divisionmultiplexing/multiple access techniques, or a combination of thesevarious techniques. In alternate embodiments, the wireless communicationsystem may utilize other communication system protocols including, butnot limited to, TDMA or direct sequence CDMA. The communication systemmay be a Time Division Duplex (TDD) or Frequency Division Duplex (FDD)system.

FIG. 2 illustrates a sequence of radio frames 200 suitable forcommunicating in the wireless communication systems of the variousembodiments. A radio frame 210 of the may comprise multiple subframes212, with each subframe having a specified duration. Some non-limitingexamples are described below. In FIG. 2, at least some subframes containa resource assignment control channel portion 214, e.g., a physicaldownlink control channel (PDCCH) and/or an enhanced PDCCH (EPDCCH), anda data channel portion 216 for data-carrying traffic, e.g., a physicaldownlink shared channel (PDSCH) or a physical uplink shared channel(PUSCH). In FDD system, the PUSCH is an uplink frequency band, whereasthe PDCCH/EPDCCH and PDSCH are in a downlink frequency band. In FIG. 2,a super frame may also be structured as a number of radio frames 210,220, 230, etc. The non-control portions of the subframe may also includepositioning reference signals (PRS) and other non-payload carryingsignals. Typically, the control channels utilize Quadrature Phase ShiftKeying (QPSK) modulation and convolutional encoding, whereas datachannels (PDSCH, PUSCH, etc) utilize QPSK/16-QAM/64QAM modulations andturbo coding with hybrid automatic repeat request (HARQ) protocol.Downlink control signaling is carried by control channels. The PDCCH islocated at the start of each downlink subframe (up to the first threeOFDM symbols) and the EPDCCH is being introduced in LTE Rel-11 islocated on one or more RB-pairs spanning both slots in the subframe.Each of these channels can carry the downlink scheduling assignment,uplink scheduling grants, UL transmit power control commands, etc.

For orthogonal frequency division multiple access (OFDMA) systems, thefrequency domain is divided into subcarriers. For example, a 5 MHz OFDMAcarrier may be divided into 300 subcarriers, with a subcarrier spacingof 15 kHz. An OFDMA subframe is also divided into multiple OFDM symbolsin the time domain. For example, a subframe may occupy approximately 1ms and contain 14 OFDM symbols (each symbol may have a cyclic prefix),wherein each symbol occupies approximately 1/14 ms. The subcarriers aregrouped to form resource blocks (RBs) that have either physicallycontiguous subcarriers or noncontiguous subcarriers. A virtual resourceblock is a resource block whose subcarriers are non-contiguous infrequency, whereas a localized RB is an RB whose subcarriers arecontiguous in frequency. Virtual RBs may provide improved performancedue to frequency diversity while localized RBs may be beneficial infrequency-dependent scheduling. In one implementation, the subframe isdivided into two slots, each of duration approximately 0.5 ms. An RB (ora physical RB) may be defined as a set of subcarriers within a slot. Aresource block pair may be defined as a pair of resource blocks, whereina first resource block is in a first slot of the subframe and a secondresource block may be in a second slot. In a localized virtual RB pair,the PRBs are localized, whereas in a distributed virtual Resource block,the RBs are distributed. Typically, the resource allocation may beperformed in units of VRB pairs.

FIG. 3 illustrates the communication of resource assignments, e.g.,Physical Resource Block (PRB) assignments, by the BS to a UE in adownlink message 300 which is also known as Downlink Control Information(DCI). In FIG. 3, a first assignment field 310 indicates the number andlocation of the PRBs assigned to the UE from the set of availableresources (e.g. PRBs). The UE may be identified by a UE Identifier orRadio Network Temporary Identifier (RNTI) which may be explicitlyindicated in the message field or implicitly encoded with the CyclicRedundancy Check (CRC) code. In some embodiments, the message 300 alsoincludes an MCS Index field 320 to provide a reference or informationthat the US uses to determine an appropriate Modulation and CodingScheme (MCS). In some embodiments the UE uses the information in the MCSindex field to determine an appropriate Transport Block Size (TBS).Particularly, the UE uses the reference in the MCS index field 320 totransport block size (TBS) from a TBS table as described further below.

FIG. 4 illustrates an embodiment of a DCI element 400 for conveying anMCS 420 to a UE. The DCI message may include a 3-bit header and aresource assignment block 410 having N-bits, that is, the number of bitsnecessary to convey resource assignments to a single UE or to a UEgroup. In the DCI of FIG. 4, the MCS field 420 accommodates a 5 bitreference, but the number of bits could be more or less depending on theamount of information to be conveyed. The DCI element 400 may alsoinclude padding bits 430 and cyclic redundancy check (CRC) bits 440 asshown. It is noted that the DCI format size also depends on variousother factors including the system bandwidth, MIMO or non-MIMO mode,transmission mode, etc. In 3GPP LTE systems, the DCI element is sent tothe UE via the PDCCH and/or EPDCCH. Other protocols may use otherappropriate link messages.

As discussed, in 3GPPP LTE Rel-8/9/10, a UE determines the transportblock size (TBS), which translates to a corresponding data rate,associated with a physical downlink shared channel (PDSCH) or a physicaluplink shared channel (PUSCH) based on downlink control information(DCI). The downlink control information indicates the number of assignedResource Blocks (RBs) and location in a carrier and a Modulation andCoding Scheme (MCS) index. Based on the number of assigned RBs and MCSindex, the UE determines the associated transport block (TB) size usinga TBS lookup table (LUT). The LUT in LTE Rel-8/9/10 was designedassuming a reference configuration (Physical Control Format IndicatorChannel (PCFICH)=3, (that is, a control region of 3 OFDM symbols withthe first data symbol starting on the 4^(th) OFDM symbol), 2Cell-Specific Reference Signal (CRS) ports, normal DL subframe, withnormal CP (i.e., implying presence of 14 OFDM Symbols in a 1 mssubframe)) and a set of reference MCSs.

FIG. 5 illustrates a representative TBS size table stored in memory ofthe UE. Each row of the table 500 corresponds to an MCS Index and eachTBS size column corresponds to a particular PRB allocation. For example,column 503 corresponds to 1-PRB, column 505 corresponds to 2-PRBs,column 506 corresponds to 3-PRBs and column 509 corresponds to 4-PRBs.The table 500 continues for a number of PRBs and for a number of MCSIndex positions. The 5 bit MCS Index field provides for a maximum binaryvalue of “11111”, which provides up to 31 base ten index positions. TheUE may use the table 500 in conjunction with the assignment information,that is, the mobile station's PRB assignments, received from a messageas exemplified in FIG. 3 or FIG. 4 to determine a TBS size. In oneembodiment, the TBS size table corresponds to a legacy TBS Table e.g.,Table 7.1.7.2.1-1, Transport block size table in the 3GPP LTE spec36.213 v 10.5.0. The modulation order and transport block size index isobtained from the MCS Index using e.g., Table 7.1.7.1-1: Modulation andTBS index table for PDSCH in LTE spec 36.213 v 10.5.0.

3GPP RANI is discussing a new carrier type (NCT) in the context ofCarrier Aggregation (CA) wherein the new carrier could have a reduced oreliminated legacy control region and/or a reduced or eliminatedCell-specific Reference Signal (CRS) overhead for improved spectralefficiency. If the legacy control region is eliminated, then the numberof resource elements available per Resource Block (RB) pair canpotential increase by at least ( 1/14)=˜6% for the normal Cyclic Prefix(CP) case. Therefore, for a given MCS, the number of information bitscan also potentially increase by, e.g., ˜6%, improving data rate by asimilar amount. Compared to the reference configuration where thecontrol region is 3 OFDM symbols with 2 CRS ports the increase can be upto 30% given 120 subcarriers for legacy RB pair and 156 subcarriers fora new RB pair without the legacy control region (e.g., PDCCH) andwithout CRS resource elements.

The NCT however may not have the same amount of variability for dynamicconfigurations as LTE Rel-8. For example, the NCT may have only 1-portCRS (e.g., that is transmitted in 1 out of 5 DL subframes), and nophysical downlink control channel (PDCCH), i.e. equivalent to PCFICH=0.The NCT may have a configurable CSI-RS (i.e., transmitted with a minimumperiodicity of every 5 ms), and there may be several subframes in aRadio Frame without CSI-RS. In summary, it is possible that the numberof REs per PRB pair in a NCT may be meaningfully larger than that usedfor the LTE Rel-8/9/10 TBS table design. There is a potential for datarate improvement by adapting the transport block size determination forthe case on NCT.

In practice, the configurations (e.g., PDCCH duration, number of CRSREs, number of CSI-RS REs, etc.) vary dynamically on each sub frame,i.e., the number of resource elements (REs) available in a PRB pair isdynamically varying. In 3GPP LTE Rel-8/9/10, for simplicity the TBSlookup is invariant to the number of available resource elements forboth UL and DL. For example, the number of REs varies from 112-132 forfrequency division duplex (FDD). There is an even greater variation inthe downlink pilot time slot (DwPTS) region for time division duplex(TDD) within each of the assigned RBs. With this simplicity, rather thanadjusting TBS for every configuration, the 3GPP LTE specification allowsthe TBS to be fixed, but the coding rate (defined as (TBS+associated CRCoverhead)/(modulation order*number of available REs used for PDSCH))varies based on the dynamic configuration. However, for the Rel-8/9/10TDD special sub frame, since the DwPTS region is quite shortened (i.e.,number of OFDM symbols on DL is quite smaller: 30-40% smaller), a fixedscaling factor (e.g., 0.75) was introduced, wherein the UE applies ascaling factor to the number of assigned RBs to obtain a referencenumber of RBs, which is then used to lookup the TBS table.

FIG. 6 is a schematic block diagram of the main components of a UE inaccordance with the present disclosure, and is not intended to be acomplete schematic diagram of the various components and connectionsthere-between required for a mobile station. The UE may thus comprisevarious other components and connections not shown in and still bewithin the scope of the present disclosure. The UE 600 comprisesgenerally user interfaces 601, at least one processor 603, and memory606. The user interfaces 601 may be a combination of user interfacesincluding but not limited to a keypad, touch screen, voice activatedcommand input, and gyroscopic cursor controls. The mobile station alsohas a graphical display 611, which may also have a dedicated processorand/or memory, drivers etc. which are not shown. The mobile station 600also comprises one or more transceivers, such as wireless transceivers613 and 615. Transceivers 613 and 615 may be for communicating withvarious wireless networks using various standards such as, but notlimited to, EUTRA, UMTS, E-UMTS, E-HRPD, CDMA2000, 802.11, 802.16, etc.

The memory may have storage sufficient for a UE operating system,applications and general file storage. Memory 606 is for illustrativepurposes only and may be configured in a variety of ways and stillremain within the scope of the present disclosure. For example, memory606 may be comprised of several memory elements of the same or differenttypes (e.g., volatile, non-volatile, etc.) each coupled to the processor603. Further, separate processors and memory elements may be dedicatedto specific tasks such as rendering graphical images upon a graphicaldisplay. In any case, a TBS Table 609 is stored in memory. For example,the TBS Table 609 may be stored on one, or more, computer readable mediasuch as one or more flash memories, one or more Compact Disc's (CD's),one or more DVDs, on or more EEPROMs, etc, and may be transferred to andfrom various network entities such as eNBs, controllers and, withrespect to FIG. 6, mobile stations. The TBS Table 609 may therefore betransported on such computer readable media and loaded into memory ofvarious network entities and/or mobile devices as needed. Additionally,the TBS Table 609 may be downloaded or uploaded via wireline (such asover the Internet) or via Over-the-Air (OTA) upgrades that may fromtime-to-time be performed to upgrade UEs that access the network. Forexample, a network operator may, via any suitable approach such as, butnot limited to, OTA upgrades, provide the TBS Table 609 to the UE of itssubscribers. The TBS Table may be provided to a base station via anysuitable approach including, but not limited to, uploading to ordownloading from, a central storage point such as, for example, a RadioOperation and Maintenance Center (OMCR).

In the process 700 of FIG. 7, at 710, the UE receives a resourceallocation indicating a number of allocated resource blocks andfrequency locations of the allocated resource blocks in a carrier. InFIG. 6, the processor 603 includes functionality that controls thetransceiver 615 for this purpose. The processor may be implemented as adigital processor that executes transceiver control instructions storedin memory. Alternatively, the processor may be implemented as anequivalent hardwired circuit or as a combination of hardware andsoftware that performs the transceiver control.

In FIG. 7, at 720, the UE determines a TBS column indicatorrepresentative of a number of RBs based on the number of allocated RBs,an adjustment factor, and a limiting factor. The TBS column indicatorcorresponds to a column in the TBS size table stored on the UE memoryand is used to obtain the TBS as described further below. The TBS columnindicator is determined by applying the adjustment factor to the numberof allocated resource blocks and comparing a result of applying theadjustment factor to the number of allocated resource blocks to thelimiting factor. The TBS column indicator is selected as either theresult or the limiting factor as the based on the comparison.Particularly, if the result of the application of the adjustment factorto the number of allocated resource blocks is greater than the limitingfactor, then the TBS column indicator is set to correspond to thelimiting factor. If the result of the application of the adjustmentfactor to the number of allocated resource blocks is less than thelimiting factor, then the TBS column indicator is set to correspond tothe result. The TBS column indicator is a positive integer and hence ifthe result is not an integer, a ceil function, floor function or arounding operation is performed.

In FIG. 6, the processor 603 includes TBS column indicator determinationfunctionality that controls the transceiver 615 for this purpose.Alternatively, the processor is implemented as an equivalent hardwiredcircuit or as a combination of hardware and software that performs theTBS column indicator determination.

In some embodiments, an adjustment factor is not applied to the numberof allocated resource blocks. If the adjustment factor is not applied,then the TBS column indicator is determined directly from the number ofallocated RBs indicated in the resource allocation. Examples ofscenarios where the adjustment factor is not applied follow. In oneembodiment, the adjustment factor is applied to the number of allocatedresource blocks only if the number of allocated resource blocks belongsto a predefined set of resource block allocation sizes. In oneembodiment, each value in the set is no greater than the total number ofresource blocks in the system bandwidth. In another embodiment, the sethas values that form a subset of a possible number of allocatableresource blocks indicatable via the resource allocation signaled to theUE. The UE obtains the set via higher layer signaling from a networkinfrastructure entity like the base station. In another embodiment, theadjustment factor is applied to the number of allocated resource blocksonly if a modulation order indicator in the resource allocationcorresponds to a particular modulation order. In yet another embodiment,the adjustment factor is applied only if the resource allocation isreceived in a control channel that spans a limited frequency portion ofthe carrier of the number of allocated RBs and spans an entire subframe.

In one embodiment, the carrier is either a legacy FDD carrier having alegacy synchronization format or a non-legacy FDD carrier having anon-legacy synchronization format and the adjustment factor associatedwith the carrier is dependent on a synchronization signal format of thecarrier. For instance, when the synchronization format is legacy, theadjustment factor may be equal to 1 (or not applied), whereas if thesynchronization format is non-legacy, the adjustment factor may be equalto a number greater than 1, e.g., 1.3. The adjustment factors may berepresentative of the expected available number of resource elements ina resource block on the carrier. Thus, a non-legacy carrier may haveless overhead and hence can accommodate larger transport block sizeswithin the same number of resource blocks. In another embodiment, thecarrier is either a legacy FDD carrier having a legacy pilot signalformat or a non-legacy FDD carrier having a non-legacy pilot signalformat and the adjustment factor associated with the carrier isdependent on a pilot signal format of the carrier. For instance, whenthe pilot signal format is legacy, then the adjustment factor may beequal to 1 (or not applied), whereas if the pilot signal format isnon-legacy, the Adjustment Factor may be equal to e.g. 1.3. TheAdjustment factors may be representative of the expected availablenumber of resource elements in a resource block on the carrier. Thus, anon-legacy carrier may have less overhead (e.g. non-legacy pilot signalsent less often or less frequently) and hence can accommodate largertransport block sizes within the same number of resource blocks.

In one embodiment, the adjustment factor is generally greater than 1 andless than 2. For 3GPP LTE implementations, the adjustment factor couldbe any one of the following factors: 1.1, 1.2, 1.3, 1.125, 1.25, 1.375,1.5, 1.625, or 1.75. These factors correspond to approximately 10%, 20%,30%, 12.5%, . . . increase in the data rate relative to the legacy datarate. In one embodiment, the adjustment factor associated with thecarrier is predetermined based on whether or not a certain referencesymbol type <Channel State Information Reference Signal (CSI-RS) ispresent in the RBs of a subframe.

In one embodiment, the limiting factor corresponds to a total number ofresource blocks in a system bandwidth associated with the carrier of thenumber of allocates resource blocks allocated to the UE. In one 3GPP LTEimplementation, the limiting factor is 110, and in another LTEimplementation the limiting factor is 100. In one embodiment, thelimiting factor is a limit resource block number that is signal to theUE by the BS or by some other entity.

In FIG. 7, at 730, the UE obtains a TBS from a TBS Table based on theTBS Column Indicator and a MCS index using the TBS/MCS component 605described above. In FIG. 6, the processor includes TBS acquisitionfunctionality 605 enabling the UE to access the TBS Table 609 in memory606 to determine TBS for a given resource assignment. Thus the processormay access TBS Table 609 using the determined TBS column indicator andthe MCS index to lookup TBS for a given assignment. The processor may bereadily implemented as a digital processor that executes TBSdetermination instructions stored in memory. Alternatively, theprocessor may be implemented as an equivalent hardwired circuit or as acombination of hardware and software that performs the TBS acquisition.In FIG. 7, at 740, the UE communicates, e.g., transmits and/or receives,using the transport block sized obtained. The transport block size maybe used by the encoder (e.g., the encoder for creating PUSCH) in thetransmitter or utilized by the decoder (e.g., the decoder for decodingPDSCH) in the receiver. In an encoder, a transport block may beprocessed, segmented, CRC attached, encoded using turbo encoder,rate-matched, scrambled and modulated for transmission. In the decoder,a received transmission is decoded by performing corresponding decodingsteps to obtain a decoded transport block.

On a NCT, the number of resource elements per PRB pair (for normal CP)is 12 subcarriers×14 OFDM symbols=168 REs. The number of demodulationreference signals (DMRS) REs for per physical resource block (PRB) pairPDSCH demodulation is 12 for Rank-2, and The number of DMRS REs for perPRB pair PDSCH demodulation is 24 for Rank>2. Therefore, the number ofREs for PDSCH per PRB pair can be 156 or 144. Consider the LTE Rel-8 TBStable with a 98 RB allocation and MCS=26; if the same TBS LU is used,then the TBS for I_MCS=28, (I_TBS=26,N_RB=98) is 73712 and using 64-QAM.Note that the I_MCS=28 corresponds to an I_TBS=26 and therefore the TBStable look-up may be performed either based on I_MCS directly or usingI_TBS derived (e.g. included in the standard specification) from theI_MCS. For NCT, this corresponds to:

A coding rate=(73712+14*24)/(98*156*6)=0.807 and a spectral efficiencyof 4.84, substantially smaller than the Rel-8 design where is wentcloser to 5.58. (Note: 14*24 refers to the CRC overhead associated withthe transport block size 73712); and

A coding rate=(73612+14*24)/(98*144*6)=0.875 and a spectral efficiencyof 5.25, smaller than the Rel-8 design where was closer to 5.58(˜0.93*6).

In some cases, an EPDCCH may occupy some resource blocks within asubframe, and in such subframes, the PDSCH in the subframe may not beassigned all resource blocks i.e., a PDSCH may be assigned smallernumber of resource blocks than the total number of resource blockswithin the system bandwidth. Note an EPDCCH and PDSCH may not bemultiplexed within a single PRB pair, i.e., EPDCCH and PDSCH may befrequency division multiplexed. For example, if an EPDCCH occupies 2 RBsin a subframe, then for 20 MHz system, a PDSCH in the correspondingsubframe may be limited to a TBS=73712 (I_TBS=26, N_RB=98) i.e., thePDSCH may be assigned a maximum of 98 Resource Blocks within thesubframe. However, if the PDSCH starting point is OFDM Symbol 0 (i.e. iflegacy PDCCH region is eliminated or PCFICH=0), then it should be ableto accommodate highest TBS=75376 even with 98 RBs assigned for PDSCH.Thus, a scaling factor which moves the TBS look-up to a large number ofRBs than the allocated number of RBs would be desirable. For a 5 MHzsystem, it could imply a loss of −6% peak data rate (if 23-RB TBS lookupis performed with 2 RBs for EPDCCH).

According to one aspect of the disclosure, it desirable to maintain thesame peak rate in later LTE releases as in LTE Rel-8 for a givebandwidth. As described above, based on one or more of an adjustment orScale Factor, which is signaled or fixed in specification, carrier type(e.g., new or legacy), EPDCCH configuration, PDSCH starting positionconfiguration information, when a UE is allocated a number of resourceblocks and a MCS index (these are sent within DCI typically) the UEdetermines its TBS based on a lookup, then the UE can look-up the TBSusing the 36.213 TBS tables and the following reference number of RBs:

N _(RB-ref) =f(AdjF,N _(RB-allocated) ,N _(RB-SystemBW)); or

N _(RB-ref) =f(AdjF,N _(RB-allocated) ,N _(RB-LTE)) or

N _(RB-ref)=min(Floor(AdjF·N _(RB-allocated)),N _(RB-LTE)) or

N _(RB-ref)=min(Ceil(AdjF·N _(RB-allocated)),N _(RB-LTE))

where N_(RB-allocated) is the number of allocated or assigned RBs (senttypically in Downlink Control Information), N_(RB-SystemBW) is typicallythe number of RBs corresponding to the system bandwidth (sent typicallyin higher layer signaling such as Physical Broadcast Control Channel(PBCH) or Radio Resource Control (RRC) signaling, etc), N_(RB-ref) isthe resultant reference RB (or a TBS column indicator) which is used asa pointer to look up a TBS Look-up table, and N_(RB-LTE) is a bandwidthvalue which can used for limiting the reference number of Resourceblocks. N_(RB-LTE) can, for example be set equal to N_(RB-SystemBW) orto another value such as 100 (or 110). 100 corresponds a systembandwidth of 20 MHz which is the largest bandwidth for one carrier and110 corresponds to the maximum value of TBS column indicator designed inthe 3GPP specification for transport blocks mapped to one spatial layer(most of the illustrated examples are for one spatial layer). Setting itto the system bandwidth is advantageous in that it improves spectralefficiency and also it keeps the same peak data rate for a givenbandwidth. Setting it to another value enables the system to supportlarger peak rates for smaller bandwidths. For example, with 5 MHz (25RBs), the current peak rate (for two spatial streams) is given by18336*2=36662 or 36.66 Mbps (18336 corresponds to the largest TBS valuebased on TBS lookup with 25 RBs (i.e., 5 MHz corresponds to 25 RBs)).Now, if the AdjF=1.1, then the reference number of RBs is 28 RBs,implying a new peak rate of 2*20616=41 Mbps, which is 10% higher. Recall18336 is the largest allocatable TBS with 25 RBs, whereas 20616correspond to largest TBS allocatable with 28 RB. The TBS LUT is in TS36.213. f( ) denotes a function that returns a valid resultant referenceRB. Min(a,b) denotes the minimum function which returns the minimum ofthe two inputs. AdjF is an adjustment factor which is used in thefunction that determines the resultant reference RB (or the TBS columnindicator) to look-up. Other approximations may be also defined as oneof ceil(x), round(x), and floor(x) or other functions that return aninteger for any real value of x. Floor(x) is the largest integer smallerthan or equal to x. Ceil (x) is the smallest integer larger than orequal to x and round(x) denotes the integer closest to x. Following areadditional example for

N _(RB-ref)=min(Min(ceil(AdjF·N _(RB-allocated)),1),N _(RB-SystemBW))

N _(RB-ref)=min(Round(AdjF·N _(RB-allocated)),N _(RB-SystemBW))

The adjustment factor (AdjF) may be determined based on the followingmotivation: Since the LTE Rel-8 TBS was designed assuming 120 REs perPRB pair available for PDSCH and since there is at least 144 to 156 REsper PRB pair for the NCT (and/or EPDCCH), then AdjF may be 144/120(=1.2) and/or 156/120 (=1.3). The Adjustment factor can be signaled orfixed in the standard specification.

Instead of a ceiling function, a floor function, rounding or otherapproximation to a nearest integer can be performed. Also, if only thepeak data rate is of concern, for reduced testing, the adjustment can beapplied only to large MCS indexes (e.g., only to MCS27, MCS28) and/orlarge RB allocation (relative to the DL system BW) where the peak datarates are relevant. The same motivations also apply to UL wherein theother signals in the subframe (e.g. sounding reference signals, ChannelState Information (CSI), uplink acknowledgements (UL ACKs) may reducethe amount of resources used for data transmission on the PUSCH. ForPeak rate purposes, the scaling factor may be applied when some of theother signals are absent (or configured not to be present by higherlayer signaling) in a subframe.

According to another aspect of the disclosure, it is desirable keep atleast same peak rate for later LTE releases as LTE Rel-8 for the samesystem BW. For example, if EPDCCH RBs are a part of a PDSCH RBallocation when looking up the TBS. In this instance, the DCI may signalan RB allocation for PDSCH, but the RB allocation may overlap withEPDCCH that contained the corresponding DCI and hence in this case, theactual PDSCH RB allocation may be obtained by taking the RB allocationcontained in the DCI and subtracting the RBs used by EPDCCH.

At the higher end of PRB allocations (i.e. UE being assigned a largenumber of PRBs for PDSCH), it is desirable to still hit the peak datarate even though the current TBS LUT does not allow it. This can be doneby using an Adjustment Factor that is additive rather thanMultiplicative in nature. The adjustment can be defined to be appliedonly when a certain threshold is reached.

-   -   If N_(RB-allocated) falls within a range of [RB1, RB2]), then

N _(RB-ref)=min(N _(RB-allocated)+δ_(Adj) ,N _(RB-SystemBW), . . . )otherwise

N _(RB-ref) =N _(RB-allocated) end if

The reference number of RBs (or TBS column indicator) may then be usedto look-up the TBS table. The concept can be generalized to multipleranges. With above idea, the adjustment is applied to only a range of RBallocations, where the spectral efficiency impact may be considered moremeaningful.

For a 20 MHz system (i.e. N_(RB-SystemBW)=100), [RB1, RB2]=[51,100], andδ_(Adj)=5, implying that a 95 RB allocation could achieve 75.376 Mbpswith a single stream (or single spatial layer) instead of 71.172 Mbps.

Ex 1: N _(RB-ref) = min(Ceil(AdjF · N _(RB-allocated) ), N _(RB-LTE) )with AdjF = 1.2, and N _(RB-LTE) = N _(RB-SystemBW) . Ex 2: N _(RB-ref)= min(min(floor(AdjF · N _(RB-allocated) ),1),N _(RB-LTE) )) with AdjF =1.2, and N _(RB-LTE) = N _(RB-SystemBW) . Ex 3: N _(RB-ref) =min(floor(AdjF · N _(RB-allocated) ,1), N _(RB-LTE) ) with AdjF = 1.2,and N _(RB-LTE) = 100. Ex 4: δ_(Adj) = Ceil(0.1* N _(RB-SystemBW) ) If N_(RB-allocated) falls within a range of [ Ceil(0.6* N _(RB-SystemBW) ),N _(RB-SystemBW) ], then N _(RB-ref) = min(N _(RB-allocated) + δ_(Adj),N _(RB-SystemBW) ) else N _(RB-ref) = N _(RB-allocated) end if

According to another aspect of the disclosure, the TBS table isredesigned. For LTE applications such a re-designed table would requirea standardized change for NCT. The same or a similar set of 29 MCSlevels as LTE Rel-8 and the same or similar set of TBS from Rel-8 areused. However a new 29×110 TBS table is generated based on aNCT-specific reference configuration (e.g., assuming 144 or 156 REs/PRBpair). In some aspects this new table may provide similar results asprevious ideas for some MCS, RB combinations, but it would be better asit is designed to better match the NCT configuration. This alternativehowever would prevent reuse of the legacy Rel-8/9/10 TBS table.

Consider 5 MHz system bandwidth example

Rel-8 allows I_TBS=26, #RBallocated=25=>Peak TBS=18336.

If EPDCCH=2RBs=>#RB allocated=23=>Peak TBS=16992.

Assume NCT with no CRS ports and no PDCCH region, and 24 DMRS REs foreight layers DMRS. Then each RB has 12×14−24=144 REs per PRB pairassuming PDSCH starts at OFDM symbol 0 (i.e. no PDCCH). The Rel-8 TBStable was designed for #REs=120/PRB pair. Thus, if there are more REs,then the TBS can potentially be scaled by an effective gain factor thatshould be close to 144/120=1.2. However, with CSI-RS/zero-power CSI-RSand other factors, we may be able to adjust of fix the scaling factor to1.1 to 1.2 (or 1.3 if we allow for even more overhead reduction) basedon higher layer signaling and applicable to the case when EPDCCH isused. For a 23-RB allocation,

No change=>TBS=16992=>33.8 Mbps (assuming 2 spatial streams)

Example 1=>TBS=16992, =>˜33.8 Mbps (assuming 2 spatial streams) for 23RB allocation and assuming no Scale_Factor, 5 MHz system BW.Example 2—=>TBS=18336, =>˜36.6 Mbps (assuming 2 spatial streams) for 23RB allocation and asssuming Scale_Factor=1.2, and a limiting factor of25 RBs (N_(RB-LTE)=25) 5 MHz system BW.Example 3—=>TBS=19848, =>˜39.6 Mbps (assuming 2 spatial streams) for 23RB allocation and asssuming Scale_Factor=1.2, and a limiting factor of100 RBs (N_(RB-LTE)=100) 5 MHz system BW.Example 2 can provide ˜10% larger data rate than Rel-8 data of rate for23 RB allocation (for 5 MHz).Example 3 can provide ˜20% larger data rate than Rel-8 data of rate for23 RB allocation (for 5 MHz).

TABLE 1 Snapshot of Rel-8/9/10 single layer TBS lookup table. TBS ValueTBS Value TBS Value TBS No Change with Ex 2 with Ex 3 index (N_(RB−ref)= 23) (N_(RB−ref) = 25) (N_(RB−ref) = 27) 0 616 680 744 1 808 904 968 21000 1096 1192 3 1320 1416 1544 4 1608 1800 1928 5 2024 2216 2344 6 24082600 2792 6 2792 3112 3368 8 3240 3496 3752 9 3624 4008 4264 10 40084392 4776 11 4584 4968 5544 12 5352 5736 6200 13 5992 6456 6968 14 64567224 7736 15 6968 7736 8248 16 7480 7992 8760 16 8248 9144 9912 18 91449912 10680 19 9912 10680 11448 20 10680 11448 12576 21 11448 12576 1353622 12576 13536 14688 23 12960 14112 15264 24 14112 15264 16416 25 1468815840 16992 26 16992 18336 19848

TABLE 2 TBS values for different MCS-levels when #RBallocated = 23,#RBSystemBW = 25 (5 MHz). TBS Value TBS Value TBS Value No Change withEx 1 with Ex 3 TBSindex (N_(RB−ref) = 23) (N_(RB−ref) = 25) (N_(RB−ref)= 27) 0 616 680 744 1 808 904 968 2 1000 1096 1192 3 1320 1416 1544 41608 1800 1928 5 2024 2216 2344 6 2408 2600 2792 6 2792 3112 3368 8 32403496 3752 9 3624 4008 4264 10 4008 4392 4776 11 4584 4968 5544 12 53525736 6200 13 5992 6456 6968 14 6456 7224 7736 15 6968 7736 8248 16 74807992 8760 16 8248 9144 9912 18 9144 9912 10680 19 9912 10680 11448 2010680 11448 12576 21 11448 12576 13536 22 12576 13536 14688 23 1296014112 15264 24 14112 15264 16416 25 14688 15840 16992 26 16992 1833619848

Instead of defining adjustment factors and reusing legacy TBS tables, itmay also be possible to add new rows to the TBS tables (e.g., bydefining I_TBS=27, 28, 29) and defining a new set of transport blocksizes for the following: 27<=I_TBS<=29 and N_RB=1, 2 . . . 110.

These new TBS indices may be used to define new TBS values that allowlarger peak rate for a given resource allocation. For instance thesethree new rows may be used by using the same 5-bit MCS index andredefining a new enhanced TBS index and enhanced Modulation Orderlook-up as below. Rather than MCS Indices 28,29,30. Alternatively, otherMCS Indices may be utilized instead.

Legacy Legacy Enhanced Enhanced MCS Modulation TBS TBS Modulation IndexOrder Index Index Order I_(MCS) Q_(m) I_(TBS) I_(TBS) Q_(m) 0 2 0 0 2 12 1 1 2 2 2 2 2 2 3 2 3 3 2 4 2 4 4 2 5 2 5 5 2 6 2 6 6 2 7 2 7 7 2 8 28 8 2 9 2 9 9 2 10 4 9 9 4 11 4 10 10 4 12 4 11 11 4 13 4 12 12 4 14 413 13 4 15 4 14 14 4 16 4 15 15 4 17 6 15 15 6 18 6 16 16 6 19 6 17 17 620 6 18 18 6 21 6 19 19 6 22 6 20 20 6 23 6 21 21 6 24 6 22 22 6 25 6 2323 6 26 6 24 24 6 27 6 25 25 6 28 6 26 26 6 29 2 reserved 27 6 30 4 28 631 6 29 6

A higher layer signaling may configure the UE to use either legacy TBSindex and/or legacy modulation order determination to utilize theenhanced TBS index and/or enhanced modulation order determination. TheMCS index signaled in the DCI may thus be used for determining themodulation order and an associated transport block index which can befurther used to lookup the transport block size table. It is possible tohave single table that determines the Modulation order and TBS based onan input MCS index. Thus, the transport block size from a TBS tableobtained based on the TBS column indicator and a modulation and codingscheme (MCS) index using either the MCS index directly or by determininga TBS index based on MCS index and using the TSB index for looking upthe TBS table.

For instance the following shows an example values for I_TBS=27 28 and29, obtained by using scaling factors of 1.1, 1.2 and 1.3, respectively.Basically, this is similar to taking the transport block sizescorresponding to the I_TBS=26 and multiplying respectively with thecorresponding scaling factor, approximating the result to nearestinteger smaller than the result of the multiplication and then furtherapproximating the result to the nearest supported TBS value. Thesupported set of TBS values is given e.g. by the legacy TBS table (toavoid creating new TBS values which may require new decoder testingeffort).

For 1 RB to 50 RB allocations, the new transport block sizes (forI_TBS=27,28,29) are showing the following table. For ease ofunderstating the transport block for legacy index I_TBS=26 is also shownin the following table.

I_TBS = I_TBS = I_TBS = I_TBS = NRBs 26 27 28 29 1 712 776 840 936 21480 1608 1800 1928 3 2216 2408 2664 2856 4 2984 3240 3624 3880 5 37524136 4584 4968 6 4392 4776 5352 5736 7 5160 5736 6200 6712 8 5992 67127224 7736 9 6712 7480 7992 8760 10 7480 8248 9144 9912 11 8248 9144 991210680 12 8760 9528 10680 11448 13 9528 10296 11448 12216 14 10296 1144812216 13536 15 11064 12216 13536 14112 16 11832 12960 14112 15264 1712576 14112 15264 16416 18 13536 14688 16416 17568 19 14112 15264 1699218336 20 14688 16416 17568 19080 21 15264 16992 18336 19848 22 1641618336 19848 21384 23 16992 18336 20616 22152 24 17568 19080 21384 2292025 18336 19848 22152 23688 26 19080 20616 22920 24496 27 19848 2215223688 25456 28 20616 22920 24496 26416 29 21384 23688 25456 27376 3022152 24496 26416 28336 31 22920 25456 27376 29296 32 23688 26416 2833630576 33 24496 27376 29296 31704 34 25456 28336 30576 32856 35 2545628336 30576 32856 36 26416 29296 31704 34008 37 27376 30576 32856 3516038 28336 31704 34008 36696 39 29296 31704 35160 37888 40 29296 3170435160 37888 41 30576 34008 36696 39232 42 30576 34008 36696 39232 4331704 35160 37888 40576 44 32856 36696 39232 42368 45 32856 36696 3923242368 46 34008 37888 40576 43816 47 35160 39232 42368 45352 48 3516039232 42368 45352 49 36696 40576 43816 46888 50 36696 40576 43816 46888

For 51RB to 110 RB allocations, the new transport block sizes (forI_TBS=27,28,29) are showing the following table. For ease ofunderstating the transport block for legacy I_TBS=26 is also shown inthe following table.

I_TBS = I_TBS = I_TBS = I_TBS = NRBs 26 27 28 29 51 37888 42368 4535248936 52 37888 42368 45352 48936 53 39232 43816 46888 51024 54 4057645352 48936 52752 55 40576 45352 48936 52752 56 40576 45352 48936 5275257 42368 46888 51024 55056 58 42368 46888 51024 55056 59 43816 4893652752 57336 60 43816 48936 52752 57336 61 45352 48936 55056 59256 6245352 48936 55056 59256 63 46888 51024 57336 61664 64 46888 51024 5733661664 65 48936 52752 59256 63776 66 48936 52752 59256 63776 67 4893652752 59256 63776 68 51024 55056 61664 66592 69 51024 55056 61664 6659270 52752 57336 63776 68808 71 52752 57336 63776 68808 72 52752 5733663776 68808 73 55056 61664 66592 71112 74 55056 61664 66592 71112 7555056 61664 66592 71112 76 55056 61664 66592 71112 77 57336 63776 6880873712 78 57336 63776 68808 73712 79 57336 63776 68808 73712 80 5925663776 71112 75376 81 59256 63776 71112 75376 82 59256 63776 71112 7537683 61664 68808 73712 75376 84 61664 68808 73712 75376 85 61664 6880873712 75376 86 63776 71112 75376 75376 87 63776 71112 75376 75376 8863776 71112 75376 75376 89 66592 73712 75376 75376 90 66592 73712 7537675376 91 66592 73712 75376 75376 92 68808 75376 75376 75376 93 6880875376 75376 75376 94 68808 75376 75376 75376 95 71112 75376 75376 7537696 71112 75376 75376 75376 97 71112 75376 75376 75376 98 73712 7537675376 75376 99 73712 75376 75376 75376 100 75376 75376 75376 75376 10175376 75376 75376 75376 102 75376 75376 75376 75376 103 75376 7537675376 75376 104 75376 75376 75376 75376 105 75376 75376 75376 75376 10675376 75376 75376 75376 107 75376 75376 75376 75376 108 75376 7537675376 75376 109 75376 75376 75376 75376 110 75376 75376 75376 75376

For 20 MHz, a Resource Block pair contains 14×12=168 Resource Elements.Assuming 4/8 DMRS ports the number of REs reserved for DMRS per RB pairis 24. Thus, there are up to 168−24=144 REs per PRB pair. With 100 RBs(20 MHz), the number of subcarriers is 100×144=14400. Thus, if atransport block of size 75376 is used, then the coding rate for a 64-QAMModulation PDSCH that is assigned 100 RBs is given by(75376+14*24)/(14400*6)=0.875. However, the Rel-8 3GPP enables a UE todecode a transport block up to a coding rate of 0.93. Thus, for theabove resource allocation example, it is possible to use a transportblock size of 78704, which implies a 3/75˜4% data rate enhancements.

Assuming 2 DMRS ports the number of REs reserved for DMRS per RB pair is12. Thus, there are up to 168−12=156 REs per PRB pair. With 100 RBs (20MHz), the number of subcarriers is 100×156=15600. In this case the TBScan be increased from 75376 to 84760, implying 14% data rateenhancement.

The scaling or adjustment may be applied instead to the transport blocklook-up after reading the TBS table. For instance, a baseline TBS_L1 istaken from the (I_(TBS), N_(PRB)) entry of Table 7.1.7.2.1-1 of theRel-8/9/10 one layer transport block lookup, which is then translatedinto TBS enhanced using a mapping as shown in a Table. For a givenRel-8/9/10 TBS looked up value, the enhanced TBS value may be obtainedby rounding (or approximating) the product of Rel-8/9/10 TBS looked upvalue and an adjustment factor to a nearest preferred TBS value. Notethat the nearest preferred TBS value may be selected from a set ofvalues e.g. that are already supported in the legacy TBS table and maybe further limited to only TBS values supported for a fixed number oflayers (i.e., one layer). For some values of TBS_L1 (e.g.,TBS_L1=75376), the enhanced TBS value may be limited to the same aslegacy TBS value (i.e., TBS_enh=75376) to simplify implementation (i.e.,UE's decoder may not be able to support a TBS greater than 75376 becauseof the UE category definition (a UE category is an indicator ofcapability of the decoder). A Rel-8/9/10 UE of category 3, it supports amaximum number of a transport block bits of 75376 within one subframeand maximum transport block bits within a subframe of 102048. Therefore,the result may be capped by a limiting factor such as a TBS limitingfactor which may be e.g., determined based on the UE category orsignaled via higher layer signaling. For example, the following tablesshows an enhanced TBS value for each TBS value looked-up in the legacytable, the three values for each TBS values correspond to the adjustmentfactors 1.1 (corresponds to TBS_E1), 1.2 (corresponds to TBS_E2), and1.3 (corresponds to TBS_E3), respectively.

The following table shows an enhanced TBS value for each TBS value(between 16 and 1192) looked-up in the legacy table, the three valuesfor each TBS values correspond to the adjustment factors 1.1(corresponds to TBS_E1), 1.2 (corresponds to TBS_E2), and 1.3(corresponds to TBS_E3), respectively.

TBS_Translation_Table 1 TBS TBS_E1 TBS_E2 TBS_E3 16 16 16 16 24 24 24 3232 32 40 40 40 40 40 56 56 56 72 72 72 72 88 88 88 88 104 120 104 120120 136 120 136 144 152 136 152 152 176 144 152 176 176 152 176 176 208176 208 208 224 208 224 256 280 224 256 256 288 256 280 296 328 280 296336 376 288 328 344 376 296 328 344 376 328 344 392 424 336 376 408 440344 376 408 440 376 408 456 488 392 424 472 504 408 440 488 536 424 472504 552 440 488 520 568 456 504 552 584 472 520 568 616 488 536 584 632504 552 600 648 520 568 616 680 536 584 648 696 552 600 648 712 568 616680 744 584 648 696 744 600 648 712 776 616 680 744 808 632 696 744 808648 712 776 840 680 744 808 872 696 776 840 904 712 776 840 936 744 808904 968 776 840 936 1000 808 872 968 1064 840 936 1000 1096 872 968 10321128 904 1000 1096 1160 936 1032 1128 1224 968 1064 1160 1256 1000 10961192 1288 1032 1128 1224 1352 1064 1160 1288 1384 1096 1192 1320 14161128 1224 1352 1480 1160 1288 1384 1480 1192 1320 1416 1544

The following table shows an enhanced TBS value for each TBS value(between 1224 and 7992) looked-up in the legacy table, the three valuesfor each TBS values correspond to the adjustment factors 1.1(corresponds to TBS_E1), 1.2 (corresponds to TBS_E2), and 1.3(corresponds to TBS_E3), respectively.

TBS_Translation_Table 2 TBS TBS_E1 TBS_E2 TBS_E3 1224 1352 1480 16081256 1384 1480 1608 1288 1416 1544 1672 1320 1480 1608 1736 1352 14801608 1736 1384 1544 1672 1800 1416 1544 1672 1864 1480 1608 1800 19281544 1672 1864 1992 1608 1736 1928 2088 1672 1864 1992 2152 1736 19282088 2280 1800 1992 2152 2344 1864 2024 2216 2408 1928 2088 2344 25361992 2216 2408 2600 2024 2216 2408 2600 2088 2280 2536 2728 2152 23442600 2792 2216 2408 2664 2856 2280 2536 2728 2984 2344 2600 2792 29842408 2664 2856 3112 2472 2728 2984 3240 2536 2792 2984 3240 2600 28563112 3368 2664 2984 3240 3496 2728 2984 3240 3496 2792 3112 3368 36242856 3112 3368 3752 2984 3240 3624 3880 3112 3368 3752 4008 3240 36243880 4264 3368 3752 4008 4392 3496 3880 4136 4584 3624 4008 4392 47763752 4136 4584 4968 3880 4264 4584 4968 4008 4392 4776 5160 4136 45844968 5352 4264 4776 5160 5544 4392 4776 5352 5736 4584 4968 5544 59924776 5160 5736 6200 4968 5544 5992 6456 5160 5736 6200 6712 5352 59926456 6968 5544 6200 6712 7224 5736 6200 6968 7480 5992 6712 7224 77366200 6712 7480 7992 6456 7224 7736 8504 6712 7480 7992 8760 6968 77368248 9144 7224 7992 8760 9528 7480 8248 9144 9912 7736 8504 9144 99127992 8760 9528 10296

The following table shows an enhanced TBS value for each TBS value(between 8248 and 73536) looked-up in the legacy table, the three valuesfor each TBS values correspond to the adjustment factors 1.1(corresponds to TBS_E1), 1.2 (corresponds to TBS_E2), and 1.3(corresponds to TBS_E3), respectively.

TBS_Translation_Table 3 TBS TBS_E1 TBS_E2 TBS_E3 8248 9144 9912 106808504 9528 10296 11064 8760 9528 10680 11448 9144 9912 11064 11832 952810296 11448 12216 9912 11064 11832 12960 10296 11448 12216 13536 1068011832 12960 14112 11064 12216 13536 14112 11448 12576 13536 14688 1183212960 14112 15264 12216 13536 14688 15840 12576 14112 15264 16416 1296014112 15264 16992 13536 14688 16416 17568 14112 15264 16992 18336 1468816416 17568 19080 15264 16992 18336 19848 15840 17568 19080 20616 1641618336 19848 21384 16992 18336 20616 22152 17568 19080 21384 22920 1833619848 22152 23688 19080 20616 22920 24496 19848 22152 23688 25456 2061622920 24496 26416 21384 23688 25456 27376 22152 24496 26416 28336 2292025456 27376 29296 23688 26416 28336 30576 24496 27376 29296 31704 2545628336 30576 32856 26416 29296 31704 34008 27376 30576 32856 35160 2833631704 34008 36696 29296 31704 35160 37888 30576 34008 36696 39232 3170435160 37888 40576 32856 36696 39232 42368 34008 37888 40576 43816 3516039232 42368 45352 36696 40576 43816 46888 37888 42368 45352 48936 3923243816 46888 51024 40576 45352 48936 52752 42368 46888 51024 55056 4381648936 52752 57336 45352 48936 55056 59256 46888 51024 57336 61664 4893652752 59256 63776 51024 55056 61664 66592 52752 57336 63776 68808 5505661664 66592 71112 57336 63776 68808 73712 59256 63776 71112 75376 6166468808 73712 75376 63776 71112 75376 75376 66592 73712 75376 75376 6880875376 75376 75376 71112 75376 75376 75376 73712 75376 75376 75376 7537675376 75376 75376

Typically, the number of resource elements in a subframe or a resourceblock is based on several dynamic (number of OFDM symbols used forcontrol region, number of DMRS ports used for PDSCH scheduling, etc) andsemi-static parameters (presence of CSI-RS signals, CRS, etc), subframetypes (regular or Multicast-Broadcast Single Frequency Networksubframe), carrier type (new carrier or a legacy carrier), etc.Therefore, the adjustment factor used may be determined as follows:

A semi-static signalled or a predefined set of adjustment factors (e.g.set may be [1.125, 1.25, 1.375, 1.5, 1.75])

The adjustment factor used for a particular communication may beselected from the set based on one or more of the following

-   -   Subframe type (regular or MBSFN)    -   Carrier type (new or legacy carrier)    -   Subframe index    -   Control channel used for sending the downlink control        information    -   A search-space within which the DCI is received by the UE    -   A control channel aggregation-level on which the DCI is received        by the UE    -   A field within the DCI that indicates the adjustment factor    -   A value of MCS index field/other fields within the DCI    -   A cyclic prefix size used

In LTE, subframes can be of different types and each subframe type mayhave a different number of REs reserved for reference signals, etc.Thus, a higher layer signaling of adjustment factors may include abitmap (or a field map), wherein each bit (or field) indicates anadjustment factor used for a particular subframe (i.e. based on asubframe index) and the bit map may have a periodic pattern. A normalsubframe may have a first adjustment factor (e.g. 1), and a second MBSFNsubframe may have a second adjustment factor (e.g. 1.3).

An adjustment factor may depend on the control channel used for sendingthe DCI message. For instance if a legacy control channel is utilized(PDCCH), then a first adjustment factor (e.g. 1) may be applied, and ifan enhanced control channel (e.g. EPDCCH) is utilized, then a secondadjustment factor (e.g. 1.3) may be used. It is possible to apply theadjustment factor irrespective of the control channel type also. Thus,legacy carrier data rate may also be improved is supportable.

An adjustment factor may depend on the search space of control channelused for sending the DCI message. For instance if a common search spaceis utilized (PDCCH/EPDCCH), then a first adjustment factor (e.g. 1) maybe applied, and if an enhanced or UE-specific search space us utilized(PDCCH/EPDCCH) is utilized, then a second adjustment factor (e.g. 1.3)may be used. Typically, such a scheme allows fallback wherein a UE canalways receive PDSCH reliably based on DCI sent in common search spaceand when UE-specific search may be ambiguous due to change inconfiguration of the UE-specific search space.

An adjustment factor may depend on a control channel aggregation-levelon which the DCI is received by the UE. For instance if aggregationlevels four or eight is utilized legacy (with PDCCH/EPDCCH), then afirst adjustment factor (e.g. 1) may be applied, and if aggregationlevels one or two is utilized legacy (with PDCCH/EPDCCH), then a secondadjustment factor (e.g. 1.3) may be used. Typically an aggregation levelindicates the amount of resources used for sending the control channeli.e. lower aggregation levels may imply less control resource usage. InRel-8, a 1, 2, 4, 8 aggregation levels corresponds to 36, 72, 144 and288 REs, respectively.

An adjustment factor may depend on value of MCS index field within theDCI. For instance if MCS index corresponds to QPSK and/or 16QAM, a firstadjustment factor (e.g. 1) may be applied, and if MCS index correspondsto 64-QAM, then a second adjustment factor (e.g. 1.3) may be used.Typically, if peak rate is of concern the adjustment factor may beimportant at the higher modulation order.

An adjustment factor may depend on value of Cyclic Prefix type of thesubframe or the carrier. For instance if a cyclic prefix is of extendedtype, a first adjustment factor (e.g. 1) may be applied, and if a cyclicprefix is of normal type then a second adjustment factor (e.g. 1.3) maybe used. Typically, a carrier with an extended CP type may have smallernumber of REs per resource block compared that of a normal CP type.

In many of the above example, instead of a first adjustment factor of 1,it may be possible to apply no adjustment factor, but the secondadjustment factor is always used.

If the limiting factor is not applied to upper limit the RB look, it maybe used in another way. For instance, if UE obtains with an effective#RBs that is greater than 110 (maximum single layer TBS columnindicator), then the two layer TBS translation table may be utilized,for example, if the result is 120, since a TBS column indicator of 120is not in one-layer TBS LUT (in Rel-8), the approach used for MIMO Rel-8(TB mapped to 2-layers) may be reused. Basically, we would assume that asingle layer TBS table can support only 110 RBs, and any larger numberof RBs would be supported using multi-layer TBS table. For the 120 RBs,a ceil (120/110) is performed to obtain an effective number of MIMOlayers=2. Then 120/2=60 is the number of RBs per layer. We first look upa 1-layer TBS (one-layer LUT in Rel-8) corresponding to a 60 RBallocation and get a result TB1, then use a 1-layer to 2-layer TBStranslation table (1-to-2 layer translation table, a second LUT, also inRel-8) and TB1 to get TB2, which would correspond to effective #RBs=120.This approach can be generalized to support any adjustment factor.

${EffectiveNumberLayers} = {{Ceil}\left( \frac{{Ceil}\left( {{AdjF} \cdot N_{{RB} - {allocated}}} \right)}{N_{{RB} - {LTE}}} \right)}$

and effective number of 1-layer

${TBS} = {{EffectiveOneLayerRBs} = {{{Ceil}\left( \frac{{Ceil}\left( {{AdjF} \cdot N_{{RB} - {allocated}}} \right)}{EffectiveNumberLayers} \right)}.}}$

Then the 1-layer TBS is looked-up with TBS indicator given byEffectiveOneLayerRBs and the MCS index. Then the resulting 1-layer TBSis translated using a one-layer-to-EffectiveNumberLayers TBS translationtable to obtain the resulting TBS value. Note that Rel-8/9/10specification describes TBS translation tables forone-layer-to-two-layers, one-layer-to-three-layers,one-layer-to-four-layers.

While the present disclosure and the best modes thereof have beendescribed in a manner establishing possession and enabling those ofordinary skill to make and use the same, it will be understood andappreciated that there are equivalents to the exemplary embodimentsdisclosed herein and that modifications and variations may be madethereto without departing from the scope and spirit of the inventions,which are to be limited not by the exemplary embodiments but by theappended claims.

1. A wireless communication terminal comprising: a transceiver; memorystoring a transport block size table; and a processor coupled to thememory and to the transceiver, the processor configured to determine atransport block size (TBS) column indicator representative of a numberof resource blocks based on a number of allocated resource blocks, anadjustment factor, and a limiting factor, the number of allocatedresource blocks indicated in a resource allocation received by thewireless communication terminal, the processor configured to obtain atransport block size from the transport block size table, the transportblock size obtained based on the TBS column indicator and a modulationand coding scheme index.